Plant house devoted to carnivorous plants.(Knight Ridder Newspapers)

GRAND RAPIDS, Mich. _ The evil meat-eaters are ravenous in Grand Rapids.

Butterworts are drooling over gnats. Sundews are sending come-hither signals to ants. Pitcher plants are drowning hapless moths.

It's dinner on the fly.

You can almost hear the plants licking their lips _ actually, their modified leaves _ and murmuring the carnivorous plant mantra:

"Let us prey."

When the Kenneth E. Nelson Carnivorous Plant House opened last month at the Frederik Meijer Gardens, it became the Midwest's only all-carnivorous conservatory and one of just a few in the nation devoted to this bizarre group of plants that trap and digest insects.

Some people might be surprised at the idea of plants taking such an active role in their own survival, but good adaptations make for evolutionary success. Look, for instance, at pollination and how bright colors and sweet nectar are calling cards for bees and ants.…